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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 2、根据Date对象获取当前的日期和时间，根据不同时间段显示不同的问候语
function greeting(hour){
if(hour < 6){return "凌晨好！"}
else if (hour < 9){return "早上好！";}
else if (hour < 12){return "上午好！";}
else if (hour < 14){return "中午好！";}
else if (hour < 17){return "下午好！";}
else if (hour < 19){return "傍晚好！";}
else if (hour < 22){return "晚上好！";}
else {return "夜里好！";}
} -->
</head>

<body>
    <input type="button" id="btn" value="点我" onclick="say()">
    <script>
        function greeting(hour) {
            if (hour < 6) {
                return "凌晨好！"
            } else if (hour < 9) {
                return "早上好！";
            } else if (hour < 12) {
                return "上午好！";
            } else if (hour < 14) {
                return "中午好！";
            } else if (hour < 17) {
                return "下午好！";
            } else if (hour < 19) {
                return "傍晚好！";
            } else if (hour < 22) {
                return "晚上好！";
            } else {
                return "夜里好！";
            }
        }

        function say() {
              var hour = new Date().getHours;
              document.write(greeting(hour)); 
        }
    </script>
</body>

</html>